To test the influence of binder strength, porous concretes with 4 binder strengths between 30.0-135.0 MPa and 5 void ratios between 15%-35% were tested. The results indicated that for the same aggregate, the rates of ...To test the influence of binder strength, porous concretes with 4 binder strengths between 30.0-135.0 MPa and 5 void ratios between 15%-35% were tested. The results indicated that for the same aggregate, the rates of strength reduction due to the increases in void ratio were the same for binders with different strengths. To study the influence of aggregate size, 3 single size aggregates with nominal sizes of 5.0, 13.0 and 20.0 mm （Nos. 7, 6 and 5 according to JIS A 5001） were used to make porous concrete. The strengths of porous concrete are found to be dependent on aggregate size. The rate of strength reduction of porous concrete with small aggregate size is found to be higher than that with larger aggregate size. At the same void ratio, the strength of porous concrete with large aggregate is larger than that with small aggregate. The general equations for porous concrete are related to compressive strength and void ratio for different binder strengths and aggregate sizes.展开更多
The modern Yellow River delta is formed near the estuary of the Yellow River with the characteristics of short formation time, efficient sedimentation rate and loose structure which make sediments prone to be compacte...The modern Yellow River delta is formed near the estuary of the Yellow River with the characteristics of short formation time, efficient sedimentation rate and loose structure which make sediments prone to be compacted and consolidate under the geostatic stress and overburden stress. It is one of the key areas with land subsidence disasters in China, bringing a series of safety hazards to production and living. Based on the data of massive surface cores and ten drill holes ranging from 12 to 40 m obtained from the northern modern Yellow River subaqueous delta, the inversion method suitable for the calculation of consolidation settlement characteristics of the modern Yellow River subaqueous delta is discussed, and the consolidation settlement characteristics of the delta sediments are inversed and predicted in this paper. The actual void ratio of the delta sediments at the depth from 3 to 15 m shows a significant power function relationship with the depth, while the void ratio of the sediments below 15 m changes little with depth. The pre-consolidation settlement(from deposition to sampling) of the delta sediments is between 0.91 and 1.96 m, while the consolidation settlement of unit depth is between 9.6 and 14.0 cm m^(-1). The post-consolidation settlement(from sampling to stable) of the subaqueous delta sediments is between 0.65 and 1.56 m in the later stage, and the consolidation settlement of unit depth is between 7.6 and 13.1 cm m^(-1) under the overburden stress. The delta sediments with a buried depth of 3 to 7 m contribute the most to the possible consolidation settlement in the later stage.展开更多
Numerical simulations are performed to examine the packing behavior of human red blood cells(RBCs). A combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs are modeled as no-friction and no-adhes...Numerical simulations are performed to examine the packing behavior of human red blood cells(RBCs). A combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs are modeled as no-friction and no-adhesion solid bodies. The packed volume and the void ratio of a large number of randomly packed RBCs are clari?ed,and the effects of the RBC shape, the mesh size, the cell number, and the container size are investigated. The results show that the packed human RBCs with normal shape have a void ratio of 28.45%, which is slightly higher than that of the ?at or thick cells used in this study. Such information is bene?cial to the further understanding on the geometric features of human RBCs and the research on RBC simulations.展开更多
The relationship between fracture toughness VGC and critical void growth RC/RO was studied for ten kinds of Steel. The macroscopic fracture toughness VGC was determined by using notched tensile specimens. and the micr...The relationship between fracture toughness VGC and critical void growth RC/RO was studied for ten kinds of Steel. The macroscopic fracture toughness VGC was determined by using notched tensile specimens. and the microscopic parameters of critical void growth ratio RC/RO were quantitatively measured under SEM. Then, the coefhcient C in the relation VGC = C In(RC/RO) proposed in author's past work was specifically explored. The correlation of C with tensile proderty parameter φ=σyδ/(Eφn) was presented for the Steel investigated, and the effects of low temperature on C were also discussed. Results show that the coefficient C is linearly related to the parameter and insensitive to low temperature.展开更多
One of the conventional ways to improve the mechanical behavior of soils is to mix them with cementing agents such as cement, lime and fly ash. Recently, introduction to alternative materials or sub-products that can ...One of the conventional ways to improve the mechanical behavior of soils is to mix them with cementing agents such as cement, lime and fly ash. Recently, introduction to alternative materials or sub-products that can be adopted to improve the soil strength is of paramount importance. Therefore, the present study aims to investigate the effects of porosity(h), dry unit weight(gd) of molding, cement content(C)and porosity/volumetric cement content ratio(h/Civ) or void/cement ratio on the unconfined compressive strength(quor UCS) of silty soileroof tile waste(RT) mixtures. Soil samples are molded into four different dry unit weights(i.e. 13 kN/m^3, 13.67 kN/m^3, 14.33 kN/m^3 and 15 kN/m^3) using 3%, 6% and 9%cement and 5%, 15% and 30% RT. The results show that with the addition of cement, the strength of the RT esoil mixtures increases in a linear manner. On the other hand, the addition of RT decreases quof the samples at a constant percentage of cement, and the decrease in porosity can increase qu. A dosage equation is derived from the experimental data using the porosity/volumetric cement content ratio(h/C_(iv)) where the control variables are the moisture content, crushed tile content, cement content and porosity.展开更多
The purpose of the study is to analyze the breeding ratio of a supercritical water cooled fast reactor (SCFR) and to increase the breeding core of SCFR. The sensitivities of assembly parameters, core arrangements and ...The purpose of the study is to analyze the breeding ratio of a supercritical water cooled fast reactor (SCFR) and to increase the breeding core of SCFR. The sensitivities of assembly parameters, core arrangements and fuel nuclide components to the breeding ratio are analyzed. In assembly parameters, the seed fuel rod diameter has higher sensitivities to the conversion ratio (CR) than the coolant tube diameter in blanket. Increasing heavy metal fraction is good to CR improvement. The CR of SCFR also increases with a reasonable core arrangement and Pu isotope mass fraction reduction in fuel, which can achieve more negative coolant void reactivity coefficient at the same time. The breeding ratio of SCFR is 1.03128 with a new core arrangement. And the coolant void reactivity coefficient is negative, which achieves a fuel breeding in initial fuel cycle.展开更多
It has been well recognized that sand particles significantly affect the mechanical properties of reconstituted sandy clays,including the hosted clay and sand particles.However,interrelation between the permeability a...It has been well recognized that sand particles significantly affect the mechanical properties of reconstituted sandy clays,including the hosted clay and sand particles.However,interrelation between the permeability and compressibility of reconstituted sandy clays by considering the structural effects of sand particles is still rarely reported.For this,a series of consolidation-permeability coefficient tests were conducted on reconstituted sandy clays with different sand fractions(ψ_(ss)),initial void ratio of hosted clays(e_(c0))and void ratio at liquid limit of hosted clays(e_(cL)).The roles of ψ_(ss) in both the relationships of permeability coefficient of hosted clay(k_(v-hosted clay))versus effective vertical stress(σ'_(v))and void ratio of hosted clay(e_(c-hosted clay))versus σ'_(v) were analyzed.The results show that the permeability coefficient of reconstituted sandy clays(k_(v))is dominated by hosted clay(k_(v)=k_(v-hosted clay)).Both ψ_(ss) and σ'_(v) affect the k_(v) of sandy clays by changing the e_(c-hosted clay) at any given σ'_(v).Due to the partial contacts and densified clay bridges between the sand particles(i.e.structure effects),the e_(c-hosted clay) in sandy clays is higher than that in clays at the same σ'_(v)v.The k_(v)-e_(c-hosted clay) relationship of sandy clays is independent of σ'_(v) and ψ_(ss)but is a function of e_(cL).The types of hosted clays affect the k_(v) of sandy clays by changing the e_(cL).Based on the relationship between permeability coefficient and void ratio for the reconstituted clays,an empirical method for determining the k_(v) is proposed and validated for sandy clays.The predicted values are almost consistent with the measured values with k_(v-predicted)=k_(v-measured)=0.6-2.5.展开更多
The architecture of the Great Pyramid at Giza is based on fascinating golden mean geometry. Recently the ratio of the in-sphere volume to the pyramid volume was calculated. One yields as result <em>R</em>&...The architecture of the Great Pyramid at Giza is based on fascinating golden mean geometry. Recently the ratio of the in-sphere volume to the pyramid volume was calculated. One yields as result <em>R</em><sub><em>V</em></sub> = π <span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span> <em><em style="white-space:normal;">φ</em></em><sup>5</sup>, where <img src="Edit_83decbce-7252-44ed-a822-fef13e43fd2a.bmp" alt="" /> is the golden mean. It is important that the number <em>φ</em><sup>5</sup> is a fundamental constant of nature describing phase transition from microscopic to cosmic scale. In this contribution the relatively small volume ratio of the Great Pyramid was compared to that of selected convex polyhedral solids such as the <em>Platonic </em>solids respectively the face-rich truncated icosahedron (bucky ball) as one of <em>Archimedes</em>’ solids leading to effective filling of the polyhedron by its in-sphere and therefore the highest volume ratio of the selected examples. The smallest ratio was found for the Great Pyramid. A regression analysis delivers the highly reliable volume ratio relation <img src="Edit_79e766ce-5580-4ae0-a706-570e0f3f1bd8.bmp" alt="" />, where <em>nF</em> represents the number of polyhedron faces and b approximates the silver mean. For less-symmetrical solids with a unique axis (tetragonal pyramids) the in-sphere can be replaced by a biaxial ellipsoid of maximum volume to adjust the <em>R</em><sub><em>V</em></sub> relation more reliably.展开更多
Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were condu...Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were conducted,with varying pressures from 400 kPa to 800 kPa,to quantitatively evaluate the densification effect in unsaturated soils.The response of surrounding soil during compaction grouting was monitored.The changes in dry density and void ratio induced by compaction grouting were obtained by monitoring volumetric water content to determine compaction efficiency.In addition,a model was developed and validated to predict the effective compaction range.The results show that soil dry density increased rapidly during compaction grouting before being stabilized at a consistent level.As expected,it is positively correlated with grouting pressures(GPs)and negatively correlated with the distance from the injection point.At higher GPs,the difference in densification effect around the injection point after compaction grouting was significant.Interestingly,variations in ultimate dry density and peak earth pressures perpendicular to the injection direction exhibited axisymmetric behavior around the injection point when comparing the dry density and earth pressure results.Furthermore,soil densification resulted in a decrease in suction.However,no significant effect of GP on suction at different soil positions was observed.Moreover,compaction efficiency decreased with increasing distance from the injection point,showing a strong linear relationship.In addition,the model results for the effective compaction range were basically consistent with the extrapolated values from the experimental results.展开更多
文摘To test the influence of binder strength, porous concretes with 4 binder strengths between 30.0-135.0 MPa and 5 void ratios between 15%-35% were tested. The results indicated that for the same aggregate, the rates of strength reduction due to the increases in void ratio were the same for binders with different strengths. To study the influence of aggregate size, 3 single size aggregates with nominal sizes of 5.0, 13.0 and 20.0 mm （Nos. 7, 6 and 5 according to JIS A 5001） were used to make porous concrete. The strengths of porous concrete are found to be dependent on aggregate size. The rate of strength reduction of porous concrete with small aggregate size is found to be higher than that with larger aggregate size. At the same void ratio, the strength of porous concrete with large aggregate is larger than that with small aggregate. The general equations for porous concrete are related to compressive strength and void ratio for different binder strengths and aggregate sizes.
基金financially supported by the Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology (No. MGQNLM-KF20 1715)the National Natural Science Foundation of ChinaShandong Joint Fund for Marine Science Research Centers (No. U1606401)+1 种基金the Special Fund of Chinese Central Government for Basic Scientific Research Operations in Commonweal Research Institutes (No. 2015G08)the National Science Foundation for Young Scientists of China (No. 41206054)
文摘The modern Yellow River delta is formed near the estuary of the Yellow River with the characteristics of short formation time, efficient sedimentation rate and loose structure which make sediments prone to be compacted and consolidate under the geostatic stress and overburden stress. It is one of the key areas with land subsidence disasters in China, bringing a series of safety hazards to production and living. Based on the data of massive surface cores and ten drill holes ranging from 12 to 40 m obtained from the northern modern Yellow River subaqueous delta, the inversion method suitable for the calculation of consolidation settlement characteristics of the modern Yellow River subaqueous delta is discussed, and the consolidation settlement characteristics of the delta sediments are inversed and predicted in this paper. The actual void ratio of the delta sediments at the depth from 3 to 15 m shows a significant power function relationship with the depth, while the void ratio of the sediments below 15 m changes little with depth. The pre-consolidation settlement(from deposition to sampling) of the delta sediments is between 0.91 and 1.96 m, while the consolidation settlement of unit depth is between 9.6 and 14.0 cm m^(-1). The post-consolidation settlement(from sampling to stable) of the subaqueous delta sediments is between 0.65 and 1.56 m in the later stage, and the consolidation settlement of unit depth is between 7.6 and 13.1 cm m^(-1) under the overburden stress. The delta sediments with a buried depth of 3 to 7 m contribute the most to the possible consolidation settlement in the later stage.
基金Project supported by the Engineering and Physical Sciences Research Council(EPSRC)Turbulence Consortium Grant(No.EP/G069581/1)the Marie Curie International Incoming Fellowship(No.PIIF-GA-253453)
文摘Numerical simulations are performed to examine the packing behavior of human red blood cells(RBCs). A combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs are modeled as no-friction and no-adhesion solid bodies. The packed volume and the void ratio of a large number of randomly packed RBCs are clari?ed,and the effects of the RBC shape, the mesh size, the cell number, and the container size are investigated. The results show that the packed human RBCs with normal shape have a void ratio of 28.45%, which is slightly higher than that of the ?at or thick cells used in this study. Such information is bene?cial to the further understanding on the geometric features of human RBCs and the research on RBC simulations.
文摘The relationship between fracture toughness VGC and critical void growth RC/RO was studied for ten kinds of Steel. The macroscopic fracture toughness VGC was determined by using notched tensile specimens. and the microscopic parameters of critical void growth ratio RC/RO were quantitatively measured under SEM. Then, the coefhcient C in the relation VGC = C In(RC/RO) proposed in author's past work was specifically explored. The correlation of C with tensile proderty parameter φ=σyδ/(Eφn) was presented for the Steel investigated, and the effects of low temperature on C were also discussed. Results show that the coefficient C is linearly related to the parameter and insensitive to low temperature.
文摘One of the conventional ways to improve the mechanical behavior of soils is to mix them with cementing agents such as cement, lime and fly ash. Recently, introduction to alternative materials or sub-products that can be adopted to improve the soil strength is of paramount importance. Therefore, the present study aims to investigate the effects of porosity(h), dry unit weight(gd) of molding, cement content(C)and porosity/volumetric cement content ratio(h/Civ) or void/cement ratio on the unconfined compressive strength(quor UCS) of silty soileroof tile waste(RT) mixtures. Soil samples are molded into four different dry unit weights(i.e. 13 kN/m^3, 13.67 kN/m^3, 14.33 kN/m^3 and 15 kN/m^3) using 3%, 6% and 9%cement and 5%, 15% and 30% RT. The results show that with the addition of cement, the strength of the RT esoil mixtures increases in a linear manner. On the other hand, the addition of RT decreases quof the samples at a constant percentage of cement, and the decrease in porosity can increase qu. A dosage equation is derived from the experimental data using the porosity/volumetric cement content ratio(h/C_(iv)) where the control variables are the moisture content, crushed tile content, cement content and porosity.
文摘The purpose of the study is to analyze the breeding ratio of a supercritical water cooled fast reactor (SCFR) and to increase the breeding core of SCFR. The sensitivities of assembly parameters, core arrangements and fuel nuclide components to the breeding ratio are analyzed. In assembly parameters, the seed fuel rod diameter has higher sensitivities to the conversion ratio (CR) than the coolant tube diameter in blanket. Increasing heavy metal fraction is good to CR improvement. The CR of SCFR also increases with a reasonable core arrangement and Pu isotope mass fraction reduction in fuel, which can achieve more negative coolant void reactivity coefficient at the same time. The breeding ratio of SCFR is 1.03128 with a new core arrangement. And the coolant void reactivity coefficient is negative, which achieves a fuel breeding in initial fuel cycle.
基金supported by the National Natural Science Foundation of China (Grant Nos.52278334 and 4197724)Fundamental Research Funds for the Central Universities (Grant No.2242024k30066).
文摘It has been well recognized that sand particles significantly affect the mechanical properties of reconstituted sandy clays,including the hosted clay and sand particles.However,interrelation between the permeability and compressibility of reconstituted sandy clays by considering the structural effects of sand particles is still rarely reported.For this,a series of consolidation-permeability coefficient tests were conducted on reconstituted sandy clays with different sand fractions(ψ_(ss)),initial void ratio of hosted clays(e_(c0))and void ratio at liquid limit of hosted clays(e_(cL)).The roles of ψ_(ss) in both the relationships of permeability coefficient of hosted clay(k_(v-hosted clay))versus effective vertical stress(σ'_(v))and void ratio of hosted clay(e_(c-hosted clay))versus σ'_(v) were analyzed.The results show that the permeability coefficient of reconstituted sandy clays(k_(v))is dominated by hosted clay(k_(v)=k_(v-hosted clay)).Both ψ_(ss) and σ'_(v) affect the k_(v) of sandy clays by changing the e_(c-hosted clay) at any given σ'_(v).Due to the partial contacts and densified clay bridges between the sand particles(i.e.structure effects),the e_(c-hosted clay) in sandy clays is higher than that in clays at the same σ'_(v)v.The k_(v)-e_(c-hosted clay) relationship of sandy clays is independent of σ'_(v) and ψ_(ss)but is a function of e_(cL).The types of hosted clays affect the k_(v) of sandy clays by changing the e_(cL).Based on the relationship between permeability coefficient and void ratio for the reconstituted clays,an empirical method for determining the k_(v) is proposed and validated for sandy clays.The predicted values are almost consistent with the measured values with k_(v-predicted)=k_(v-measured)=0.6-2.5.
文摘The architecture of the Great Pyramid at Giza is based on fascinating golden mean geometry. Recently the ratio of the in-sphere volume to the pyramid volume was calculated. One yields as result <em>R</em><sub><em>V</em></sub> = π <span style="white-space:nowrap;"><span style="white-space:nowrap;">⋅</span></span> <em><em style="white-space:normal;">φ</em></em><sup>5</sup>, where <img src="Edit_83decbce-7252-44ed-a822-fef13e43fd2a.bmp" alt="" /> is the golden mean. It is important that the number <em>φ</em><sup>5</sup> is a fundamental constant of nature describing phase transition from microscopic to cosmic scale. In this contribution the relatively small volume ratio of the Great Pyramid was compared to that of selected convex polyhedral solids such as the <em>Platonic </em>solids respectively the face-rich truncated icosahedron (bucky ball) as one of <em>Archimedes</em>’ solids leading to effective filling of the polyhedron by its in-sphere and therefore the highest volume ratio of the selected examples. The smallest ratio was found for the Great Pyramid. A regression analysis delivers the highly reliable volume ratio relation <img src="Edit_79e766ce-5580-4ae0-a706-570e0f3f1bd8.bmp" alt="" />, where <em>nF</em> represents the number of polyhedron faces and b approximates the silver mean. For less-symmetrical solids with a unique axis (tetragonal pyramids) the in-sphere can be replaced by a biaxial ellipsoid of maximum volume to adjust the <em>R</em><sub><em>V</em></sub> relation more reliably.
基金the National Natural Science Foundation of China(Grant Nos.42172298,42002289)the Shanghai Geological Star Program for their financial support.
文摘Compaction grouting is primarily applied based on empiricism,and it is challenging to quantify its densification effect.To address this issue,five sets of laboratory model tests on ideal compaction grouting were conducted,with varying pressures from 400 kPa to 800 kPa,to quantitatively evaluate the densification effect in unsaturated soils.The response of surrounding soil during compaction grouting was monitored.The changes in dry density and void ratio induced by compaction grouting were obtained by monitoring volumetric water content to determine compaction efficiency.In addition,a model was developed and validated to predict the effective compaction range.The results show that soil dry density increased rapidly during compaction grouting before being stabilized at a consistent level.As expected,it is positively correlated with grouting pressures(GPs)and negatively correlated with the distance from the injection point.At higher GPs,the difference in densification effect around the injection point after compaction grouting was significant.Interestingly,variations in ultimate dry density and peak earth pressures perpendicular to the injection direction exhibited axisymmetric behavior around the injection point when comparing the dry density and earth pressure results.Furthermore,soil densification resulted in a decrease in suction.However,no significant effect of GP on suction at different soil positions was observed.Moreover,compaction efficiency decreased with increasing distance from the injection point,showing a strong linear relationship.In addition,the model results for the effective compaction range were basically consistent with the extrapolated values from the experimental results.
